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/*-
* Copyright (c) 2018, Juniper Networks, Inc.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <sys/cdefs.h>
#include <sys/queue.h>
#include "libsecureboot-priv.h"
/*
* To support measured boot without putting a ton
* of extra code in the loader, we just maintain
* a hash of all the hashes we (attempt to) verify.
* The loader can export this for kernel or rc script
* to feed to a TPM pcr register - hence the name ve_pcr.
*
* NOTE: in the current standard the TPM pcr register size is for SHA1,
* the fact that we provide a SHA256 hash should not matter
* as long as we are consistent - it can be truncated or hashed
* before feeding to TPM.
*/
static const br_hash_class *pcr_md = NULL;
static br_hash_compat_context pcr_ctx;
static size_t pcr_hlen = 0;
static int pcr_updating = -1;
struct hashed_info {
const char *hi_path;
const char *hi_basename;
STAILQ_ENTRY(hashed_info) entries;
};
static STAILQ_HEAD(, hashed_info) hi_list;
/**
* @brief initialize pcr context
*
* Real TPM registers only hold a SHA1 hash
* but we use SHA256
*/
void
ve_pcr_init(void)
{
if (pcr_updating < 0) {
pcr_updating = 0;
pcr_hlen = br_sha256_SIZE;
pcr_md = &br_sha256_vtable;
pcr_md->init(&pcr_ctx.vtable);
STAILQ_INIT(&hi_list);
}
}
/**
* @brief get pcr_updating state
*/
int
ve_pcr_updating_get(void)
{
return (pcr_updating);
}
/**
* @brief set pcr_updating state
*/
void
ve_pcr_updating_set(int updating)
{
pcr_updating = updating;
}
/**
* @brief update pcr context
*/
void
ve_pcr_update(const char *path, unsigned char *data, size_t dlen)
{
struct hashed_info *hip;
if (pcr_updating > 0 && pcr_md != NULL) {
pcr_md->update(&pcr_ctx.vtable, data, dlen);
/* if mallocs fail, measured boot will likely fail too */
if ((hip = malloc(sizeof(struct hashed_info)))) {
hip->hi_path = strdup(path);
if (!hip->hi_path) {
free(hip);
return;
}
hip->hi_basename = strrchr(hip->hi_path, '/');
if (hip->hi_basename) {
hip->hi_basename++;
} else {
hip->hi_basename = hip->hi_path;
}
STAILQ_INSERT_TAIL(&hi_list, hip, entries);
}
}
}
/**
* @brief get pcr result
*/
ssize_t
ve_pcr_get(unsigned char *buf, size_t sz)
{
if (!pcr_md)
return (-1);
if (sz < pcr_hlen)
return (-1);
pcr_md->out(&pcr_ctx.vtable, buf);
return (pcr_hlen);
}
/**
* @brief get list of paths in prc
*/
char *
ve_pcr_hashed_get(int flags)
{
const char *cp;
char *hinfo;
struct hashed_info *hip;
size_t nbytes;
size_t x;
int n;
n = 0;
nbytes = x = 0;
hinfo = NULL;
STAILQ_FOREACH(hip, &hi_list, entries) {
nbytes += 1 + strlen(flags ? hip->hi_basename : hip->hi_path);
}
if (nbytes > 1) {
hinfo = malloc(nbytes + 2);
if (hinfo) {
STAILQ_FOREACH(hip, &hi_list, entries) {
cp = flags ? hip->hi_basename : hip->hi_path;
n = snprintf(&hinfo[x], nbytes - x, "%s,", cp);
x += n;
}
if (x > 0) {
hinfo[x-1] = '\0';
}
}
}
return hinfo;
}
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